The Molecular Cardiology Research Institute (MCRI) at the New England Medical Center is devoted to the exploration of the molecular mechanisms that underlie human cardiovascular diseases. MCRI investigators use in vitro molecular biological, cell biological and transgenic approaches to identify and validate new therapeutic targets. The investigators within the MCRI pursue varied, yet complementary avenues of research--the vast majority of which are NIH-supported. Two broad areas of research within the MCRI include vascular and cardiomyocyte biology. We examine the normal and pathophysiologic regulation and function of vasomotor tone, cardiomyocyte hypertrophy and apoptosis, cardiac development and cell proliferation. A common focus for many of the NIH-funded MCRI Investigators--those who comprise the Investigators in this proposal--is mechanisms that regulate contraction and relaxation of cardiac and vascular myocytes. In order to understand the molecular events that regulate cardiac myocyte and vascular smooth muscle cell contraction and relaxation, cellular and biochemical events are studied extensively in cultured cardiac and vascular cells, which are routinely generated, passaged and stored in our cell culture facilities. This is an efficient system for the study of cardiovascular signaling that minimizes the use of intact animals. However, at present we do not have the capacity to provide sophisticated physiological analysis of cell signaling and cell contraction and relaxation in single cells. The MCRI has thus identified the need for an imaging apparatus that can simultaneously measure cell contraction and relaxation and perform highresolution fluorescence imaging in real-time. These goals are focused on acquiring new technology in two areas: calcium imaging related to cell contraction, and signal transduction pathways and fluorescence detection of proteins to study their activity and intracellular localization. Thus, based on ongoing programs and increasing needs within the MCRI for the capacity to study cardiac and vascular cell physiology, the purpose of this proposal is to gain the support needed to build a highly integrated cell imaging system to measure real-time single cell contraction relaxation and simultaneous calcium transients. Acquisition of this system will facilitate the extensive and complementary studies of cardiovascular signal transduction within our institution.